Before formal construction of the US aircraft begins, the military will be performing a "critical design review" to explore how to better implement the improved specs, advanced technology, weaponry and computing power needed for the clandestine project, news.com.au reports.

Senior air force public affairs director Anne Stefanek said the project would advance stealth technology further then ever before and was being pursued with a sense of urgency so the US could stay ahead of rapidly advancing Russian and Chinese-built air defence technologies.

She told Warrior Maven: "The B-21 program has completed preliminary design review. The next step is critical design review. The air force remains confident in the B-21’s progress and in delivering this new capability as planned in the mid-2020s."

The critical review will focus on developing the most advanced stealth properties like coating and configuration, and heat signature suppression technologies — these features ensure radar “pings” struggle to identify an approaching bomber.

Handout - Getty

The US's current B-2 Spirit planes, pictured, have been a symbol of its superior air force for many years

A recent report from The Mitchell Institute for Aerospace Studies, The Imperative for Stealth, argued that despite new air defences being able to detect aircraft across a much wider spectrum of frequencies, stealth technology can still offer tremendous advantage for the US.

It suggested the key to outsmart advanced multi-frequency air defences could be found in “broadband stealth” — a level of stealth achieved using cross section-reducing tailless designs.

The report read: "The B-21 image released by the USAF depicts a design that does not use vertical flight control surfaces like tails.

"Without vertical surfaces to reflect radar from side aspects, the new bomber will have an RCS (Radar Cross Section) that reduces returns not only from the front and rear but also from the sides, making detection from any angle a challenge."

Advanced computer simulations are also playing a huge role in the development of technology needed to defeat modern air defences.

AFP

This image shows current US B-1B Lancer bombers flying over South Korea

Getty - Contributor

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Other than news of the "critical review" very little has been revealed about the B-21, with the bomber sold to US Congress as a cost-controlled, standardised - and 'modular' - upgrade of the proven B-2 “Spirit” stealth design.

The new B-21 is expected to carry long range, nuclear-capable cruise missiles and is supposed to be stealthy enough to fly anywhere in the world with impunity.

It has previously been revealed the US air force plans to build about 100 of the B-21 Raider Bombers at a unit cost of about $A699 million.

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